Self-locking cotter key



I July 19, 1951 SQHAEFER 2,559,737

SELF-LOCKING COTTER KEY Filed July 8, 1949 ed at their lower ends.

f atented july 16,

SELF-LOCKING COTTER KEY Frederic Schaefer, Pittsburgh, Pa., assignor to Schaefer Equipment Company, Pittsburgh, Pa., a corporation of Pennsylvania Application July 8, 1949, Serial No. 103,567

2 Claims. 1

This invention relates to cotter keys, and more particularly to such keys which are spread automatically when they are driven into place.

Cotter keys have been made in which the outer or lower end of one leg is permanently bent under the adjacent end of the other leg, so that when the loop that connects the upper ends of the legs is struck in such a manner as to drive the upper leg downward through a pin, the two legs will be forced apart. The metal rod or wire from which such keys have been made has been half round in cross section so that a cross section through both legs of a key would be round. One objection to such keys is that there is only line contact between them and the members which they hold in place on the pins through which the keys extend. The result is that where there is serious vibration the keys soon become worn and weakened, even to the breaking point. Another objection is that the stock from which the keys are made must be heavy enough to give the legs the necessary stiffness to permit the one leg to be driven past the other leg, and this stifi material either makes the loop undesirably stiff or requires that the material in the loop be thinner than in the rest of the key so that it may be more readily deformable. Of course, varying the thickness of different parts of the material forming the key increases the cost of making the key.

It is among the objects of this invention to provide a cotter key of the self-spreading type which is made from relatively thin and easily deformable material, which is made from a metal strip that is substantially uniform in thickness throughout its length, which has a readily deformable loop connecting its legs, which has one leg that is materially stiffer than the other leg to permit it to be driven ahead without buckling, and which has a rectangular or square cross section through both legs.

In accordance with this invention, the cotter key is formed from a meta1 strip which is substantially uniform in thickness throughout its length, and which is bent to provide a pair of legs connected at one end by a deformable loop. For convenience of description and claiming, the legs are referred to herein as being vertical with the loop at their upper ends, but it will be understood that the key can be used in horizontal, inverted or any other position. One of the legs extends upward beyond the other leg and is formed from inner and outer portions integrally connect- These portions are provided by doubling the strip upon itself, which doubles the thickness of the one leg and thereby 2 stiffens it considerably. The inner portion of the double leg has a free upper end inside the loop substantially in engagement with the upper, inner surface thereof. The lower end of the other leg is bent inwardly beneath the lower end of the double leg.

When the key is inserted in an object with its opposite ends projecting therefrom and the portion of the loop at the upper end of the double leg then is struck downward, the loop will be compressed to some extent and the lower end of the double leg will be driven downward past the inwardly bent lower end .of the other leg to bend the latter away from the double leg. The double leg may be provided with a stop for limiting the distance that it can be driven downward. Preferably, the metal strip from which the key is made is rectangular in cross section so that the key will fit in a rectangular hole and have fiat side surfaces. For a square hole, the strip is approximately three times as wide as it is thick. The leg portion of the key is composed of three adjoining thicknesses of the strip, thereby making it square.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. 1 is a side view of my cotter key extending through a pin on which another member be held in place, such as a railway car brake pin I, is provided with a vertical hole extending radially through it. The hole is rectangular, preferably being square. The brake pin extends through an element, such as a brake lever 2, that is held on the pin by a cotter key 3 inserted through the square hole in the pin so that the opposite ends of the key project from the top and bottom of the pin. The key has parallel vertical legs 5 and 6 that are connected at their upper ends by a loop I integral with them. One

leg 5 is longer than the other leg and extends upward beyond it, and the loop extends laterally fromthe longer leg and downward to the other one. The lower end of the loop engages the top of the pin. The key is formed from a single metal strip which is bent into the shape shown.

It is a feature of this invention that the strip is oblong in cross section with flat sides and is substantially uniform in thickness and width throughout its length. The strip is thin enough 3 to permit the loop to be deformed easily when struck by a hammer or the like, even though the strip is made of hard, wear-resistant metal. As it is preferred to use this key in square holes, the width of the strip is approximately three times as great as its thickness. The reason for this particular relation of width to thickness will now be explained. The loop and the lower or shorter eg 6 of the key are formed from a single thickness of the strip, but the upper or longer leg is twice as thick as the other leg so that it will be stiff enough to be driven down through the pin without buckling or bending over above it. The thicker leg is formed by doubling a portion of the metal strip upon itself. Consequently, the leg part of the key is formed from three thicknesses of the strip, which give a total thickness equal to the width of the strip and make the leg part of the key square in cross section, as shown in Fig. 3. The double leg 5 thus has parallel inner and outer portions 8 and 9 substantially engaging each other and integrally connected at their lower ends by a reverse bend that has a curved lower surface ill. The inner portion 8 of the leg is one end of the strip from which the key is formed and has its free end 5 1 located inside loop 2 in engagement, or nearly in engagement, with the inner surface of the loop next to the upper end of the outer portion of the double leg. The

lower end of the other leg 5 is curved inwardly beneath the curved lower surface of the double leg.

After the key has been dropped or inserted in the square pin hole as shown in Fig. l, the upper end of the loop is struck by a hammer to flatten or compress the loop to some extent and to thereby drive the stiff double leg 5 downward against the inwardly bent lower end of the other leg. 1 1e upper part of the loop will engage the free upper end i I of the inner portion 8 of the double leg and drive it downward in unison with the outer portion. This causes the weaker leg 6 with the curved lower end to be forced or bent away from the, double leg, whereby the two legs are spread apart and the key is locked in the pin as shown in Fig. 2.

It is desirable to provide a stop for limiting the distance that the double leg can be driven downward so that the loop will not be flattened, too much. This can be done by providing the metal strip before it is bent into the shape of the key, with a struck-out detent that will'project from the outer portion 8 of the double leg between the upper and lower ends of the loop. 7

When this detent strikes the pin the double leg can be driven downward no farther. The key can be removed from the pin by hammering upward on the lower end of the double leg until it has been driven upward far enough to pass the curved lower end of the other leg. This will permit the bent leg to be forced in against the straight double leg as the key is driven upward through the pin.

The square body of the key presents a flat side.

surface of considerable area to the brake lever 2 so that vibration of the lever and pin will not wear the key away. In addition to having a longer life than a circular key, this key is inexpensive to manufacture because it can be made According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A cotter key formed from a metal strip substantially uniform in thickness throughout its length which is bent to provide a pair of vertical legs connected at their upper ends by a deformable loop, one of said legs being longer than the other one and extending upward beyond it and having inner and outer portions formed by doubling the strip upon itself to stiffen the longer leg, said inner portion having a free upper and inside the loop substantially in engagement with the upper inner surface thereof, and the lower end of the shorter leg being free and bent inwardly beneath the lower end of the double leg, whereby when the key is inserted in an object with its opposite ends projecting therefrom and the portion of the loop at the upper end of the double leg is struck downward the loop will be compressed and the lower end of the double leg will be driven downward past the inwardly bent lower end of the other leg to bend the latter away from the double leg.

2. A cotter key adapted to fit in a square hole and formed from a bent metal strip of uniform ablong cross section, the width of the strip being approximately three times as great as its thickness, said key having a pair of substantially engaging legs integrally connected at their upper ends by a deformable loop, one of said legs being longer than the other one and extending upward beyond it and having substantially engaging inner and outer portions formed by doubling the strip upon itself to stiffen the longer leg and to provide its lower end with a curved surface, whereby a cross section through both legs is square, said inner portion having a free upper end inside the loop substantially in engagement with the upper inner surface thereof, and the lower end of the shorter legbeing free and curved inwardly beneath the curved lower end surface of the double leg, whereby when the key is inserted in a square hole with its opposite ends projecting therefrom and the portion of the loop at the upper end of the double leg is struck downward the loop will be compressed and the lower end of the double leg will be driven downward past the inwardly bent lower end of the other leg to bend the latter away from the double leg.

FREDERIC SCI-IAEFER'.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 395,348 Ray Jan. 1, 1889 1,056,190 Lorenz Mar. 18, 1913 1,171,536 Ostrander Feb. 15, 1916 2,015,194 Ruping Sept. 24, 1935 2,333,930 Hedstrom Nome T1943 I 

